I have a table with invoice information.  There are multiple rows for an invoice_num for each item purchased in the invoice.  The final item rung up for that particular invoice will have the total price for the invoice.  Like below

 

   invoice_num     item    quantity      price       cost      total        cust_num

                    1    socks              2     $3.00     $1.00                            111

                    1    t-shirt              1    $10.00    $5.00                           111

                    1    discount          1    -$2.00                                         111

                    1    pants              1    $20.00   $13.00   $34.00             111

                    2    t-shirt              1    $10.00    $5.00    $10.00            110

 

I am trying to create a report to grab information from all invoices that have the item 'discount' within the transaction and display the total number of uses, the distinct count of cust_num, the average sales (avg. of total).

 

Any ideas where I should start?

 

Thanks